JP2000288584A - Donor diaphragm for microorganism and production thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform effective denitrification treatment in a waste water equipment by supplying a proper amt. of a propagation factor to a microorganism without requiring special control even if load or temp. changes. SOLUTION: A diaphragm 1 isolating a microorganism and permitting a microorganism propagation factor (donor) to gradually transmit toward the microorganism has a structure different in donor transmissivity at positions 1a, 1b. This diaphragm is produced by extrusion molding, blow molding, compression molding, injection molding or vacuum molding. By this constitution, a proper amt. of the propagation factor is supplied to a microorganism through the diaphragm even if load or temp. varies and the microorganism is active efficiently to perform denitrification treatment and the disposal work of the excessive propagation factor is also omitted or reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for satisfactorily removing microorganisms by separating growth factors (donors) from microorganisms (acceptors) and gradually allowing the growth factors to permeate the microorganisms in wastewater treatment or the like using microorganisms. The present invention relates to a donor membrane for microorganisms to be grown and a method for producing the same. Particularly, in a method for removing nitrogen in wastewater by adding an organic carbon source as a hydrogen donor for denitrifying bacteria, stabilizes the treatment and reduces the treatment cost. It is suitable for a biological carrier membrane that can be reduced.

[0002]

2. Description of the Related Art As a method for removing nitrogen contained in wastewater, there is a denitrification method using microorganisms. Conventionally, a method of adding a microorganism carrier and an organic carbon source such as methanol as a hydrogen donor to a denitrification tank (biological method) Denitrification method) is known. The principle is "water treatment engineering" (edited by Tetsuo Ide, Gihodo Publishing,
1997, pp 297-303). As the above method, there is a method in which a hydrogen donor is directly charged into a denitrification tank to perform a denitrification treatment.
Japanese Patent No. 37364 discloses the contents. In this method, the liquid to be treated is circulated by a pump in order to increase the contact efficiency between the denitrifying bacteria and the organic carbon source and the liquid to be treated. In addition, since the added organic carbon source becomes excessive due to the fluctuation of the nitrogen concentration in the inflowing water to be treated and the like, and the discharge water may be deteriorated, it is devised to control the added amount of the organic carbon source. . On the other hand, a membrane separation denitrification treatment method in which organic carbon is supplied through a plastic membrane instead of directly charging a hydrogen donor into a denitrification tank as described above (Hirofumi Izawa et al., Japan Society for Water Treatment Biology, Vol. 32, Third
No. pp. 191-197 (1996)).

[0003]

However, the conventional processing method described above has the following problems. (1) A denitrification treatment method in which a hydrogen donor is directly charged
4-37364), when detecting and controlling the concentration of organic carbon (hydrogen donor: methanol is often used),
A small amount of addition makes detection difficult and equipment for quantitative detection is expensive, and even if the concentration is detected and controlled, it takes a long time for the effects (such as bacterial growth) to appear, so sudden load fluctuations occur. There are problems such as not being able to withstand. In addition, there is a problem that excess organic carbon needs to be treated to increase the COD of the wastewater, resulting in an extra cost. (2) In the denitrification treatment method in which organic carbon is provided by membrane separation (Izawa method), a small amount of organic carbon permeating a plastic (PE, silicon rubber, etc.) membrane is supplied to the denitrifying bacteria. It can be selectively fixed to the surface and the nitrogen removal efficiency can be improved. In addition, since organic carbon is not directly introduced, concentration management and treatment of excess organic carbon are not required. However, there is a problem that it cannot respond to a temperature change (summer / winter), a load change of the water to be treated, and the like. This is because the permeation amount of the above-mentioned membrane is determined by the film thickness and the material, and if the film thickness and the material are determined according to the summer or a small load, the permeation amount of the organic carbon becomes insufficient when the load is increased in the winter or when the load becomes large. When the film thickness and material are selected in accordance with the winter season or heavy load, the permeation amount of organic carbon becomes excessive when the summer season or the load becomes small, and it becomes necessary to dispose of the excess organic carbon. Because it comes. In addition, since fungi form colonies (communities), the density of the fungus varies from place to place, and the amount of organic carbon required as a nutrient source also varies from place to place. However, since the density of organic carbon permeating the membrane is the same over the entire surface (because the organic carbon permeability of the membrane is uniform over the entire surface), the organic carbon tends to be insufficient in the colony portion that requires a large amount of organic carbon, In a non-colonial part where the required amount of organic carbon is small, there is a problem that organic carbon tends to be excessive and the growth efficiency is deteriorated.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a membrane separation and denitrification treatment system which can control the concentration of organic carbon and eliminate excess organic carbon and can cope with temperature changes and load fluctuations. As a general purpose, a donor membrane capable of separating a donor microbial growth factor from an acceptor microorganism and allowing the donor to pass through the acceptor at an appropriate concentration to allow efficient growth of the microorganism is used. The purpose is to provide.

[0005]

Means for Solving the Problems To solve the above problems, the first invention of the microorganism donor membrane of the present invention is:
A donor membrane that separates a microbial growth factor that is a donor from a microorganism that is an acceptor and allows the donor to gradually pass through to the acceptor side, wherein the donor permeability has a structure that differs depending on the position. I do.

[0006] The donor membrane for microorganisms of the second invention comprises a first donor membrane.
In the invention of the present invention, the constituent material of the membrane, the thickness, the porosity of the membrane, the presence or absence of the distribution of the dispersing agent, or by changing one or more of the dispersity by the position, to vary the donor transmittance depending on the position, I do. The donor membrane for microorganisms of the third invention is characterized in that, in the first or second invention, the dispersant is an adsorbent. A fourth aspect of the present invention provides the microorganism donor membrane according to any one of the first to third aspects, wherein the constituent material of the membrane is a thermoplastic polymer, a thermosetting polymer, a rubber, and / or a mixture thereof. And The donor membrane for microorganisms of the fifth invention is characterized in that, in the first to fourth inventions, the membrane is a microorganism carrier for immobilizing microorganisms.

According to a sixth aspect of the present invention, there is provided a method for producing a donor membrane for microorganisms, comprising extruding, blow molding, compression molding, injection molding or vacuum molding the membrane according to any one of the first to fifth aspects. Features.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The diaphragm of the present invention is required to have a function of separating a microorganism growth factor as a donor from a microorganism as an acceptor and a function of gradually transmitting the donor to the acceptor. . As a material of such a film, typically, a thermoplastic polymer, a thermosetting polymer, a rubber, or a mixture thereof can be used. However, the present invention is not limited to these, and any film having the above function may be used. The thickness of this film is determined in consideration of its material, use environment, and the like. Therefore, the present invention is not limited to a specific thickness, but is generally about 50 to 500 μm. This film can be obtained by, for example, extrusion molding, blow molding, compression molding, injection molding or vacuum molding.

In the membrane of the present invention, since the conventional membrane has a uniform amount of organic carbon permeated over the entire surface, the permeability of the donor, which is a growth factor of microorganisms, is changed depending on the position. To solve the above-mentioned problem. This difference in transmittance is due to the constituent material of the film, the thickness, the porosity of the film,
This can be achieved by changing the presence or absence of the dispersing material or the dispersing rate of the dispersing material depending on the position, and these can be combined at the same position or at different positions.
The transmittance can be represented by, for example, the average amount of transmission of the donor per unit time, the maximum amount of transmission, the transmission ratio, and the like.

FIG. 1A shows a case where a thin film portion 1a is provided by locally changing the thickness of a diaphragm 1. In the thin film portion 1a,
A higher donor transmittance than the base (thick film portion) 1b is obtained. Here, q1 and q2 in the figure indicate the permeation amount of the donor per unit time and unit area. In FIG. 1B, the material (degree of diffusion) of the film is locally changed. The diffusion coefficient of the local diaphragm (high diffusion portion 10a) is larger than that of the base (low diffusion portion) 10b. I have. In the diaphragm 10, the donor transmittance of the high diffusion portion 10a is larger than that of the base 10b. FIG. 1 (C) shows a case where foaming is controlled and foaming is locally performed.
a and a base (non-foamed portion) 20b having no foam. In the foaming portion 20a, the presence of the bubbles 2... 2 promotes the permeation of the donor, and has a higher transmittance than the base portion 20b. In this example, the transmittance is changed depending on the presence or absence of bubbles. However, the transmittance can be changed by changing the dispersion density of bubbles or / and the size of bubbles depending on the location. FIG. 1D shows a state in which the dispersing material 3 is locally dispersed.
It is composed of a dispersion portion 30a in which the dispersion materials 3 are dispersed and a base portion (non-dispersion portion) 30b without the dispersion material. Dispersing unit 3
At 0a, the permeation of the donor is suppressed due to the presence of the dispersants 3..., And the transmittance is lower than that of the base. In this example, the transmittance is changed depending on the presence or absence of the dispersion. However, the transmittance can be changed by changing the dispersion density, the size of the dispersion material, and the type of the dispersion material depending on the location.

In each of the above embodiments, the donor transmittance of the diaphragm is locally changed. However, the position, width, number, etc. of the portion for changing the transmittance can be appropriately selected. A portion having a different transmittance in an island shape may be provided, or the transmittance of each region may be changed by defining a boundary. Further, an inclined portion for gradually changing the donor transmittance in the plane direction may be provided in all or a part of the diaphragm. The degree of difference in transmittance is not particularly limited. For example, a high transmittance portion is secured in consideration of a state where a large number of donors are required, and a state where a large amount of a donor is not considered. As a result, a low transmittance portion can be secured.

[0012] The diaphragm can be produced by the above-mentioned methods. In the production, the film before solidification is rolled between rolls provided with protrusions to change the thickness of the film, or an extruder, A portion having a different transmittance can be provided by intermittently feeding a different material, a foaming material, or a dispersing material with an injection machine. For example, a sheet of a molten polymer is extruded by an extruder, and the sheet is sandwiched between metal rolls having irregularities on the surface, and cooled and solidified to form a polymer sheet having irregularities on the surface.

The membrane obtained as described above is preferably used in a denitrification treatment facility, and uses an organic carbon source such as methane as a growth factor (donor) and a denitrifying bacterium as an acceptor. In that case, a step of immobilizing microorganisms may be provided in advance so that the diaphragm is used as a microorganism carrier. The arrangement method and arrangement shape of the diaphragm are not particularly limited, and they can be arranged in an appropriate shape and method according to the facility device structure and the like. In addition,
As the present invention, the types of the donor and the acceptor are not limited to the above, and it is possible to target a different donor from the above in accordance with an acceptor of a different type from the above. May be plural.

According to the diaphragm of the present invention, since the transmittance of the donor varies depending on the position, the microorganisms exhibit different growth forms depending on the position due to the difference in the transmittance. That is, an active colony is formed in a place where the transmittance is high, and a portion where the transmittance is low is a colony with low activity or a non-colony. And when the load is large or the temperature is low,
Microorganisms are active in a colony in a place having a high transmittance without a shortage of growth factors, so that desired performance such as denitrification can be effectively obtained. On the other hand, when the load is small or the temperature is high, the growth factor is consumed well in the portion where the transmittance is low and the microorganisms are active, and in the portion where the transmittance is high the growth factor is consumed by the consumption of the growth factor in the colony. Surplus is suppressed. Therefore, in selecting the transmittance, the transmittance of the high transmittance portion is determined according to the large load and low temperature, assuming load fluctuation and temperature, and the transmittance of the low transmittance portion is determined according to the low load and high temperature. It is desirable to determine. That is, according to the present invention, microorganisms are satisfactorily active even with load fluctuations and seasonal changes without performing special concentration control or the like, and the generation of extra donors is suppressed.

[0015]

As described above, according to the donor membrane for microorganisms of the present invention, the microorganism growth factor as the donor is separated from the microorganism as the acceptor, and the donor is gradually transmitted to the acceptor. Since the donor diaphragm has a structure in which the donor transmittance varies depending on the position, it is not necessary to control the concentration of the donor (for example, organic carbon) or to dispose of the excess donor,
There is an effect that the donor can be supplied so that the microorganisms can work well against a temperature change or a load change.

[Brief description of the drawings]

FIG. 1 is a partially enlarged view of a diaphragm according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 diaphragm 1a thin film part 1b base 10 diaphragm 10a high diffusion part 10b base 20 diaphragm 20a foaming part 20b base 30 diaphragm 30a dispersion part 30b base

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Claims (6)

[Claims] Claims: 1. A donor membrane for separating a donor microbial growth factor from an acceptor microorganism and allowing the donor to permeate gradually toward the acceptor, wherein the donor permeability has a structure that differs depending on the position. Donor diaphragm for microorganisms characterized by the following: 2. The method according to claim 1, wherein at least one of the constituent material and thickness of the membrane, the porosity of the membrane, and the dispersity of the dispersing material is changed depending on the position, so that the donor transmittance varies depending on the position. Donor membrane for microorganisms as described 3. The donor membrane for microorganisms according to claim 1, wherein the dispersant is an adsorbent. 4. The donor membrane for microorganisms according to claim 1, wherein the constituent material of the membrane is a thermoplastic polymer, a thermosetting polymer, a rubber, and / or a mixture thereof. 5. The donor membrane for microorganisms according to claim 1, wherein the membrane is a microorganism carrier for immobilizing microorganisms. 6. A process for producing a donor membrane for microorganisms, comprising subjecting the membrane according to claim 1 to extrusion molding, blow molding, compression molding, injection molding or vacuum molding.